Attacks from malicious software (viruses and malware) are the single largest threat to computer users today. They account for a considerable amount of financial loss as well as loss of productivity. Most gain access to systems via the Internet, but there many other ways in which malicious software is acquired as well.


Viruses are generally created to exploit a vulnerability of some sort in the software itself.  Some viruses are merely annoying - causing not much more than hindered computer performance, while others can be disastrous. Some variants can modify and destroy data, overwriting crucial files and reformatting hard drives.


Malware takes a few different forms; most commonly known by names like "spyware", "adware", "hijackers", and "toolbars". Generally they pretend to be legitimate software and are many times installed by the user (usually without knowledge of their full intent). Certain types of malware can take control of the browser, redirect search attempts, place pop-up ads onto the screen, track all of the sites a user visits, and cause a computer to become unbearably slow.

Often times it is much easier to get infected with malicious software than it is to get rid of it, especially since the most common viruses give off no symptoms of their infection and generally once you have installed malware onto your computer it tends to multiply. For users who possess little or no experience dealing with threats of this type, they can become overwhelmed very quickly.